Materials and Structures

List of Papers (Total 170)

In many countries recycling of reclaimed asphalt pavement (RAP) for road surface layers is limited to a maximum of 10–30%. This is due to technical limitation of common asphalt plant but also to specifications that are still restrictive when it comes to increasing RAP in surface courses. The mistrust in this practice is mainly related to uncertainty in performance of these mixes...

The durability of building materials with respect to salt crystallization is commonly determined by accelerated weathering tests, carried out in the laboratory. An effective laboratory weathering test should assess the durability and, in the case of conservation of historic buildings, the compatibility of repair materials with those existing. Besides, the test should provide...

This paper presents the self-healing results of asphalt mixtures by the action of capsules containing sunflower oil as encapsulated rejuvenator. Three different capsule contents, 0.10, 0.25 and 0.50% by total weight of the mixture, were added to the samples. The mechanical and thermal properties of capsules have been evaluated. In addition, the effect of the capsule addition and...

One of the main challenges in the offshore renewable energy industry is the reduction in the levelised cost of energy of wind, wave and tidal devices. The use of concrete as the primary construction material in such devices presents a low unit cost, high marine durability alternative to steel, however, to maximise material efficiency factors such as mix constituent design...

Early failure of asphalt pavements is a common issue all around the world. Damages are caused by various reasons like insufficient binder or aggregate quality, an inadequate mix design or improper handling in the production/construction process. The effects of binder, aggregates and mix design have been widely studied and state-of-the-art testing methods are available for both...

This RILEM round robin study with nine participating laboratories investigated bitumen ageing, its effect on chemical properties and its reproducibility. The impact of temperature used for short-term (RTFOT) binder ageing on the combined short- and long-term (PAV) aged samples was investigated; thereby the effect of reduced mixing temperature such as those relevant for warm mix...

Experiments have been carried out to study the influence of moisture condition, including moisture content and its distribution, on the chloride diffusion in partially saturated ordinary Portland cement mortar. The mortar samples with water-to-cement (w/c) ratios of 0.4, 0.5 and 0.6, cured for 1 year, were preconditioned to uniform water saturations ranging from 18 to 100%. The...

This study evaluates the chloride binding capacity and the migration of chloride in sodium carbonate-activated slag cements and mortars. The effect on chloride mobility and binding of adding a calcined layered double hydroxide (CLDH) to the binder mix was also assessed. Significantly improved durability characteristics can be achieved for sodium carbonate-activated slag mortars...

This paper investigates the effect of microwave curing on the bond strength of steel reinforcement in concrete repair. Pull-out tests on plain mild steel reinforcement bars embedded in four repair materials in 100 mm cube specimens were performed to determine the interfacial bond strength. The porosity and pore structure of the matrix at the steel interface, which influence the...

Drilling resistance measurement (DRM) is recognised as an important on-site micro-invasive procedure for assessment of construction materials. This paper presents a detailed investigation of user-controlled variables and their influence on drilling resistance. The study proves that the ratio of penetration rate/rotational speed is proportional to drilling resistance. Data from...

The mini-slump test is a fast, inexpensive and widely adopted method for evaluating the workability of fresh cementitious pastes. However, this method lacks a standardised procedure for its experimental implementation, which is crucial to guarantee reproducibility and reliability of the test results. This study investigates and proposes a guideline procedure for mini-slump...

Non-uniform shrinkage strains can lead to significant additional deflections in large box girder bridges, leading to serviceability problems. This article examines experimentally and analytically the effect of different cross-section geometries on the shrinkage camber of bridge box girders. Small-scale beams were tested to determine the development of shrinkage strains across the...

This paper aims to study the phase modification, reaction kinetics, mechanical properties and drying shrinkage of sodium carbonate activated slag by incorporating sodium sulfate in the activator. The results show that the reaction process is firstly controlled by CO3 2− anions, and later runs similar to that of sodium sulfate activation. Besides, the relatively unstable phase...

Damage to concrete structures may occur as a result of internal effects. Alkali silica reaction (ASR) is a long term reaction between alkalis and reactive aggregate present in the concrete. The reaction product is sodium–potasium–calcium silica gel, able to absorb water, resulting in the expansion and cracking of concrete. The key problem is to find the right method for...

In order to investigate the mechanical behavior of asphalt–aggregate systems subjected to direct shear loading and reveal the shear failure mechanism, four groups of direct shear tests were conducted on composite specimens under different experimental conditions with a self-manufactured direct shear test apparatus at 25 °C. Comparative studies were conducted to evaluate the...

A complete understanding of the mechanisms upon which a filler acts in a cement-based material, e.g. as a C–S–H nucleation and/or growth-inducing factor, is of high importance. Although various studies report on accelerated cement hydration in the presence of fillers, the reason behind these observations is not completely understood yet. This work contributes to this subject, by...

Increasingly more research is being directed towards the valorisation of waste materials as precursors for synthesising alkali-activated binders (AABs). For this study, varying blends of tungsten mining waste (TMW) and waste glass (WG) are activated using a combined sodium hydroxide (SH) and sodium silicate (SS) alkali solution. The activating solution itself is also varied with...

During the production and recycling of asphalt concrete, bitumen in contact with inorganic particles is exposed to air at high temperatures. As a result an oxidation of bitumen, also known as aging, occurs. The reaction between bitumen and air at 163 °C was studied insitu with and without the presence of inorganic impurities by means of fourier transform infrared spectroscopy in...

Bituminous binders as organic materials are prone to aging mainly by oxidation. Aging changes the viscoelastic behavior of the material over time towards higher stiffness and brittleness. FTIR has been increasingly used lately to investigate impacts of oxidative aging on the chemical structure of bitumen. Especially the carbonyl and sulfoxide bands are affected by aging and...

When a wood board is exposed to a change in relative humidity on only one of its surfaces, e.g. in case of flooring or a panel painting, the resulting asymmetric moisture content profile induces differential expansion over the thickness. Consequently a bending moment causes the board to curve. A theory is presented to describe the bending of a wood board due to a step change in...

In this paper, cement free high performance alkali activated slag-fly ash composites are designed by applying the modified Andreasen and Andersen particle packing model, and steel fibers of two lengths are applied for strength reinforcement and shrinkage compensation. The influence of the fiber length, dosage and hybrid on the fresh behavior, compressive strength, stress–stain...

The combination of environmental actions and mechanical load has obvious synergetic effects on the durability of concrete. But these effects have been widely neglected so far. For a realistic service life prediction the effect of an applied mechanical load on chloride penetration has been taken into consideration as a first and important step in RILEM TC 246-TDC since 2011. This...